We investigate the effects of variations in the value of the charitable contribution deduction on nonprofit firm behavior, including exploring for the first time the effects of the tax-price of giving on fundraising and returns to fundraising. We find that a one-percent increase in tax subsidies drives a 1.7-percent increase in fundraising, and decreases average returns to fundraising by two percent. We also find that tax subsidies deliver less than a dollar of value, net of fundraising, for each dollar foregone by the government, and that program-related expenditures are largely unresponsive to subsidies, at least in the short run. We argue that these results may imply that the charitable contribution deduction is less effective than prior research has suggested. For example, we argue our results are consistent with the hypothesis that subsidies trigger a destructive arms’ race for donor funds. The modest elasticity of real charitable output to tax price implies that tax subsidies may simply crowd out other revenue sources, such that the efficacy of the subsidy depends on the relative efficiency of these alternative sources.